1. Field of Invention
This invention relates to a system and method for improving the quality of scanned images, and more particularly, to the identifying and filtering of speckles from scanned images.
2. Description of Related Art
Photocopiers and scan-to-print image processing systems have typically been concerned with rendering the most accurate copy of the original possible. Sometimes, however, the most accurate copy producible includes imperfections arising from the original image. Although one usually desires the most accurate copy of the original, there is the occasion when customers would prefer to have the imperfections on the original image eliminated from the succeeding generation of copies.
One of the more prevalent imperfections transferred from the original image to the copy is known in the art as speckles, or pepper noise. Essentially, speckles are isolated dark spots on an image. They often arise during the scanning and printing process, and their removal is desired to improve the image quality of the copy.
To perform suppression or removal of speckles, it is known to use various de-speckle algorithms. In using a de-speckle algorithm, selectivity is key. The algorithm must suppress or remove speckles, and only speckles, from the image. Other image structures of the image such as text, halftones, graphics, etc., need to be preserved.
In addition to selectivity, a de-speckle algorithm should be efficient. This is especially true where the image path becomes more and more complex. In such circumstances, the resources that can be allocated to each component on the image path become more and more limited.
Available de-speckle algorithms are mostly designed for binary images, i.e., black and white images. There is a growing need for cost-effective grayscale de-speckle algorithms that input grayscale and color images, and output de-speckled images.